Question

A. For a relationship to be defined, we need at least two relations (tables). [2] a. TRUE b. FALSE

B. Aggregate functions can be used in a SELECT clause without GROUP BY on a column of a table [2] a. TRUE b. FALSE

C. A table which satisfies 3NF (Third Normal Form) can violate 2NF (Second Normal Form) a. TRUE [2] b. FALSE

D. In a table the foreign key attribute can have null value. a. TRUE [2] b. FALSE

E. Since Views are virtual tables, we cannot use a SELECT statement on them. a. TRUE [2] b. FALSE

F. We can define relationship between two tables without using the concept of foreign key a. TRUE [2] b. FALSE

G. We can define more than one relationship between two tables. a. TRUE [2] b. FALSE

(please give reasoning for each answer)

Answer 1

A. False: For a relationship to be defined, we need at least one relation.

B. True: "SELECT SUM(column) FROM table_name;"

C. False: A table is said to be in 3NF if it is also in 2NF.

D. True: A foreign key attribute can have NULL value.

E. False: Views are nothing but SELECT queries. "CREATE VIEW `view_name` AS SELECT statement;"

F. True: We can join two tables without using the concept of Foreign Key. Though the use of a foreign key makes the execution of the query faster, it is not necessary to define a Foreign Key for a join to perform between 2 tables.

G. True: There are 3 types of relationships that exists (One-to-one, One-to-many and Many-to-many). We can define multiple relationships between 2 tables depending on the data we are dealing with.